1. Field of the Invention
The present invention relates to a catalytic process for the manufacture of rare earth alkoxides.
2. Description of the Prior Art
A number of prior art references speak of the preparation of rare earth alkoxides using halide-containing mercury compounds or mixtures containing them as catalysts. For example, U.S. Pat. No. 3,278,571 mentions the use of mercuric chloride as a catalyst, and U.S. patent No. 3,757,412 mentions the use of mercuric iodide or a mixture of mercuric chloride and mercuric acetate. Certain literature (non-patent) references also mention the use of halide-containing mercury compounds as catalytic agents in the formation of rare earth alkoxides by reaction of an alcohol and the rare earth metal. Inorganic Chemistry, Vol. 5 (1965) pp. 342-346 discloses mercuric chloride as a catalyst for such a reaction and Inorganic Chemistry, Vol. 9 (1970) pp. 2788-2787 also mentions the use of mercuric chloride.
In the above disclosures, a mercury chloride catalyst figures prominently. However, recent work in regard to formulation of rare earth oxide-containing ceramic materials renders it highly undesirable to use a halide-containing (e.g., chloride-containing) catalyst. In those instances where the ultimate ceramic is intended for structural end use applications, the use of a chloride-containing catalyst can introduce unwanted chloride anion contamination into the final material bringing about undesired defects in the crystal lattice to the material thereby weakening it. In ceramic applications where electrical conductivity is the desired result (e.g., in metal oxide superconductors) the chloride anion impurity can undesirably alter the conductivity performance of the material.
Chloride anion impurities in the final ceramic material are substantially intractable and easy means for their removal have not been devised. Hence, there are major deficiencies in the previously described methods for forming rare earth alkoxides in accordance With a number of current programs to make ceramic materials with structural or electrical end use applications. It is to this shortcoming of these prior art procedures that the instant invention is directed.